A few decompositions of the tensor have already been presented. The first one was obtained by discrete optimization using a SAT solver. In short, we solved the set of equations (REF ) where \(p\)  contained all the elements of the factor matrix \({\bf A}\)  as independent unknown variables in the Galois field GF(2).
Recall that GF(2) contains
only two values, 0 and 1, and it holds that 1+1=0 in this field.
The other factor matrices were obtained by re-ordering the columns of \({\bf A}\)  according to
(REF ). The system of equations (REF ) for the unknown \(p\) 
was converted into the SAT problem using the Bosphorus method and software
[1]}, and solved via the solver Minisat 1.14 [2]}.
After cca 10 minutes of processing, we received a solution for \(p\)  in the Galois field.
The next step consisted of applying further symbolic computations described in
Section V.B. to assign suitable signs to the ones in \(p\) .
